Brake pad for disc brakes

ABSTRACT

A brake pad for disc brakes is provided in which the brake pad comprises a damping plate attached to the reverse face of a lining carrier plate. The damping plate is attached to the lining carrier plate by way of projections which are molded on the lining carrier plate and extend into corresponding apertures of the damping plate. The external ends of the projections are widened so that the damping plate is pressed against the reverse face of the lining carrier plate.

BACKGROUND OF THE INVENTION

This invention relates to a brake pad for disc brakes having a dampingplate fixed on the reverse face of a lining carrier plate, whereby thedamping plate reduces braking noise and provides heat insulation.

It is known in the prior art that braking noises, in particularsquealing, can be suppressed by fixing a damping plate to the reverseface of a lining carrier plate of a brake pad. The damping plate is alsosuited for heat insulation with respect to the hot brake pad of thepiston of a hydraulic actuating apparatus being pressed against thereverse face of the lining carrier plate in order to protect thehydraulic fluid from overheating and forming bubbles. Such a dampingplate is generally cemented to the reverse face of the lining carrierplate. This form of attachment, however, bears the disadvantage that thedamping plate may twist or slip away in the event of heavy strains onthe brake.

In a brake pad which is known from U.S. Pat. No. 4,846,312, ananti-twist protection is envisaged. The lining carrier plate is formedwith holes which are engaged by correspondingly shaped sections of thedamping plate. The damping plate is, however, still retained bycementing. The risk of falling out is not yet excluded in thisinvention. It is a further disadvantage that additional manufacturingcost is incurred for the configuration of the damping plate and of thelining carrier plate, as well as the cost of cementing.

It is known in the prior art to fix the damping plate to the liningcarrier plate by riveting. The riveted couplings, however, have thedisadvantage of being very rigid. It has become evident in practice thatinaccuracies due to manufacturing techniques or to heat expansion of thedamping plate and the lining carrier plate in a hot brake pad lead tobuckling-up of the damping plate which then no longer planely abuts thelining carrier plate. This will in turn deteriorate the noise abatingproperties of the damping plate.

In view of the above-referenced problems associated with brakingsystems, some attempts have been made to remedy them. For example, EP0224988 A1 teaches providing slots in the dampening plate so that whenrigid rivets are used in the brake assembly, any mechanical stress whichis developed is compensated for and damping plate buckling is prevented.Although this approach may be satisfactory in addressing the problemsassociated with damping plate buckling, this arrangement is not optimalregarding the rigidity and consistency of the damping plate and alsoregarding the manufacturing effort entailed.

SUMMARY OF THE INVENTION

It is, therefore, an object of this invention to provide a method ofattaching the damping plate to the lining carrier plate with improveddamping properties while the aforementioned disadvantages of cemented orriveted bonds are avoided.

To achieve this object in accordance with the invention, the attachmentconsists of a form of riveting by which the damping plate is anchored tothe lining carrier plate with space for movement. For this purpose, thelining carrier plate is only deformed at the attachment points.

Preferably, the rivet locations are arranged in consideration of thesurface areas of the brake pad. Preferably, the rivet locations areplaced such that they do not abut the brake piston or brake caliperduring braking. By arranging the rivet locations this way, the rivetsare not used to transmit brake clamping forces.

This form of attachment causes a slight increase manufacturing costs. Adamping plate which has been anchored in this way can neither twist norfall out and is, moreover, secured against buckling-up due to theinventive space for movement, so that it will planely abut the liningcarrier plate in any condition. No separate element, such as a rivet, isrequired for attachment.

In one preferred embodiment, the present invention is directed to abrake pad which is directly applied by the brake piston in afloating-caliper spot-type disc brake. In another preferred embodiment,the present invention relates to a disc brake pad which is indirectlyapplied by a floating-caliper and is arranged on the axial side of thefloating-caliper lying opposite the brake piston.

In order to ensure a planar abutment of the damping plate against thereverse face of the lining carrier plate, at least two attachment pointsshould be provided which are disposed in the external marginal range ofthe lining carrier plate opposite each other. Attachment points in theexternal marginal range are particularly important because the dampingplate is not normally pressed to the lining carrier plate by the pistonof the hydraulic actuating apparatus in this area. An additionalattachment point may be positioned in the center range of the liningcarrier plate. In addition to an improved attachment of the dampingplate, a spring could simultaneously be attached at this anchoring pointto retain the piston-side brake pad at the piston of the hydraulicactuating apparatus.

Patent protection is also applied for a method of manufacturing theinventive brake pad. The external ends of the projections which servefor attachment are widened, for example, by means of wobble riveting. Inthis way, the degree of deformation of the external ends can bedetermined very precisely. During wobble riveting the external ends ofthe projections are deformed such that they urge the damping plateagainst the lining carrier plate at an exactly defined pressing forcewhich has been determined to be optimum as to the damping properties fora series of brake pads to be manufactured.

Still in another preferred embodiment of the present invention, a brakepad is disclosed for use in a floating-caliper system such that thisbrake pad abuts the floating-caliper with ranges that are external in acircumferential direction of the brake disc. Two fixing points areprovided in the center range of the brake pad and in the range of arecess of the floating-caliper. Preferably, projections are shaped outof the lining carrier plate for fixing the damping plate to the liningcarrier plate. This results in reduced material and reducedmanufacturing costs compared to conventional riveting techniques.

In a preferred embodiment of the present invention, the damping plateconsists of a steel plate and is coated with rubber.

An advantageous design of this invention is achieved by providingprojection depressions on the reverse face of the lining carrier plate.In certain circumstances, a lining carrier plate of this kind may beeasier to handle within the framework of an industrial scalemanufacturer. The deformations of the lining carrier plate which serveto attach the damping plate must be formed before applying the frictionlining. Tongues of the damping plate project laterally and ovaldepressions of the backplate are disposed parallel to the relevantjuxtaposed edge of the damping plate. For low cost manufacture of thedepressions and their overhangs it is envisaged to mold them into thelining carrier plate by means of one or of a plurality of dies.

In the manufacture of brake pads of this kind inaccuracies may occurbetween the distances of the projections of the lining carrier platesprovided for attachment and the distances of the holes in the dampingplates provided for the passage of said projections which cannot easilybe balanced by means of the inventive space for movement. In that casethe damping plate of the brake pad will not evenly abut the liningcarrier plate, whereby the noise abating properties will bedeteriorated.

A further advantageous design of this invention avoids theaforementioned disadvantage by providing oblong holes at the dampingplate.

Additional embodiments of the present invention address a brake padwhich is positioned on the axial side of the floating caliper furnishedwith the brake cylinder and which is directly abutted against the brakepiston. The two projections of the lining carrier plate are, therefore,positioned in the marginal ranges which in the circumferential directionof the brake disc are situated outside the abutment surface of the brakepiston. A retaining spring which serves to retain the brake pad at thebrake piston may be attached to a third centered projection. Theretaining spring is protected against twisting by having the thirdcentered projection be D-shaped.

For the other brake pad which is positioned on the axial side of thefloating caliper opposite the brake piston, a brake pad is recommendedwherein the two projections have substantially circular cross sectionsand are positioned in external marginal ranges of the reverse face ofthe lining carrier plate. Since the ranges are situated externally inthe circumferential direction of the brake disc this brake pad isabutted against the floating caliper, therefore, the two attachmentpoints are provided in the center range of the brake pad and in therange of a recess of the floating caliper.

The projections of the brake pads which are provided for the attachmentof the damping plate are molded outward from the lining carrier plate,whereby material expenses and cost of manufacture are saved as opposedto conventional riveting.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of this invention will be described in more detail in thefollowing, making reference to the accompanying drawings, in which:

FIG. 1 is a top view of the inventive brake pad in a first embodiment;

FIG. 2 is a cross-sectional view along the line A--A of FIG. 1;

FIG. 3 is a cross-sectional view along the line B--B of FIG. 1;

FIG. 4 is a top view of the inventive brake pad in a second embodiment;

FIG. 5 is a cross-sectional view along the line C--C of FIG. 4;

FIG. 6 is a damping plate in a third embodiment;

FIG. 7 is a lining carrier plate in a third embodiment;

FIG. 8 is a brake pad in a third embodiment;

FIG. 9 is a damping plate in a fourth embodiment;

FIG. 10 is a lining carrier plate in a fourth embodiment;

FIG. 11 is a brake pad in a fourth embodiment; and

FIG. 12 is a cross-sectional view along the line D--D of FIG. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The brake pad illustrated in FIGS. 1 to 3 is furnished with a liningcarrier plate 1 whose front face is secured to a friction lining 2 andwhose reverse face is secured to a damping plate 3. The lining carrierplate 1 has five projections 4, 5, 6, 7, 8 molded outwardly from theplane and project through five holes 9, 10, 11, 12, 13 of said dampingplate 3. The external ends 14 of said projections 4, 5, 6 are widened bymeans of a wobble riveting so that they overlap the damping plate 3 attheir sides and urge it against the lining carrier plate 1. Between saidprojections 4, 5, 6, 7, 8 and said damping plate 3 a space for movements is provided which allows a slight shift of the damping plate 3 withrespect to the projections 4, 5, 6, 7, 8 in a direction which isparallel to the plane of the plate. The projection 6 serves, inaddition, to secure a retaining spring 15 whose spring arms 16, 17, 18project outwardly at a substantially right angle to the plane of thelining carrier plate 1 and engage the interior space of a hollow piston19 of a hydraulic actuating apparatus (not shown In this way the brakepad is anchored to the piston 19. Said piston 19 is outlined in FIGS. 1and 2 by dashed lines. The two projections 7 and 8 are intended as ananti-twist protection for the retaining spring 15. They do not serve toattach the damping plate 3, therefore, they are not widened at theirexternal ends.

A second embodiment of the invention is illustrated in FIGS. 4 and 5.Two oval depressions 20, 21 are molded on the reverse face of the liningcarrier plate 1 by means of a first larger-size die. The damping plate 3is formed in this embodiment with two laterally projecting tongues 22,23 which project into said depressions 20, 21. Overhangs 24, 25 areshaped out of the external walls of said depressions 20, 21 by means ofa second smaller-size die. Said tongues 22, 23 are secured under saidoverhangs 24, 25, whereby the damping plate 3 will be pressed againstthe lining carrier plate 1. Between the tongues 22, 23 and the lateralwalls of the depressions 20, 21 a space for movement s is provided whichallows a slight shift of the tongues 22, 23 in a direction which isparallel to the plane of the plate.

A third embodiment of the invention is illustrated in FIGS. 6 to 8. Adamping plate 30 is furnished with oblong holes 31, 32 which arepositioned opposite each other in the external marginal ranges in thecircumferential direction of the brake disc (not shown). Thelongitudinal extension of said two oblong holes 31, 32 runs in thedirection of their connecting line. A third, circular hole 33 isprovided in the center range of the damping plate 30. In the marginalranges of its reverse face, as seen in the circumferential direction, alining carrier plate 34 is furnished with two circular projections 35,36 and in its center range with a third projection 37 which has aD-shaped cross section.

In the finished brake pad 38 the damping plate 30 is attached to thereverse face of the lining carrier plate 34, the D-shaped projection 37projects through the third hole 33 and the two circular projections 35,36 project through the oblong holes 31, 32. Dimensional inaccuracieswhich are due to the manufacturing techniques will be balanced by saidoblong holes 31, 32, so that the damping plate 30 will evenly abut withthe lining carrier plate 34 upon riveting of the projections 35, 36. TheD-shaped projection 37 projects through an opening of a retaining spring39 which is also D-shaped. The retaining spring 39 is riveted to theprojection 37, whereby it will be secured so as to be protected againsttwisting.

The brake pad 38 is intended for use in a floating-caliper disc brake,particularly for that axial side which is furnished with a brake pistonsliding within the brake cylinder. In this configuration, the retainingspring 39 penetrates into the interior space outlined by a dashed line40 of the hollow brake piston which is directly abutted against thebrake pad 38.

A fourth embodiment illustrated in FIGS. 9 to 11 is related to anotherbrake pad 41 which is intended for use in the same floating-caliper typedisc brake, but on the axial side opposite the brake piston.

Here, the damping plate 42 is furnished with a circular hole 43 and withan oblong hole 44. The two holes 43, 44 are disposed in the radialdirection of the brake disc (not shown) on either side of the center ofthe damping plate 42 opposite each other. The lining carrier plate 45 isfurnished with two correspondingly positioned circular projections 46,47 to which the damping plate 42 is riveted. Dimensional inaccuraciesare balanced by the oblong hole 44, whereby a planar abutment of thedamping plate 42 is obtained.

In the assembled condition, the brake pad 41 is abutted to the floatingcaliper as illustrated by dashed line 48. In this configuration, twofingers of the floating caliper extend over the reverse of the brake pad41 and over the damping plate 42. The projections 46, 47 are arrangedsuch that they are positioned in a recess of the floating caliperbetween the fingers, whereby they do not interfere with the floatingcaliper.

The projections 35, 36, 37, 46, 47, which serve to attach the dampingplates 30, 42 and the retaining spring 39, are molded outwardly from thelining carrier plates 34, 45 as is illustrated in FIG. 12.

It will be apparent to those skilled in the art that the foregoingdisclosure is exemplary in nature rather than limiting, the inventionbeing limited only by the appended claims.

What is claimed is:
 1. A brake pad for a disc brake, comprising:a liningcarrier plate which is provided on its front face with a friction liningfor urging against a brake disc and on whose reverse face a dampingplate is fixed which serves for noise abatement and for heat insulation,wherein said lining carrier plate includes at least two projectionsextending from said reverse face of said lining carrier plate which aredisposed at a distance from each other, means for permitting movementduring use between said damping plate and said lining carrier plate,said means including apertures within said damping plate, each aperturerespectively associated with one of said projections, each said apertureallowing a space for movement between said aperture and saidrespectively associated projection, wherein the external ends of saidprojections are widened so that they project over the edges of therespectively associated aperture and press said damping plate againstsaid lining carrier plate, thereby allowing a slight lateral shift ofsaid damping plate relative to said lining carrier plate in a directionparallel to the plane of said lining carrier plate within the limits ofsaid space for movement.
 2. A brake pad as claimed in claim 1, whereinsaid at least two projections are disposed in an external marginal rangeof said lining carrier plate opposite each other.
 3. A brake pad asclaimed in claim 2, wherein a third projection is provided in a centerrange of said lining carrier plate whereby said third projection servesto secure a retaining spring to said brake pad.
 4. A brake pad asclaimed in claim 1, wherein widened external ends of said projections ofsaid lining carier plate are widened by means of wobble riveting.
 5. Abrake pad as claimed in claim 4, wherein said wobble riveting generatesa force which is optimum as to the damping properties for a series ofbrake pads to be manufactured.
 6. A brake pad as claimed in claim 4,wherein said wobble riveting creates a shape of said widened externalend of said projections which is optimum as to the damping propertiesfor a series of brake pads to be manufactured.
 7. A brake pad as claimedin claim 1, wherein said damping plate comprises a steel plate coatedwith rubber.
 8. A brake pad for a disc brake, with a lining carrierplate which is provided on its front face with a friction lining beingintended to be urged against a brake disc and on whose reverse face adamping plate is fixed which serves for noise abatement and/or for heatinsulation, comprising:at least two projections extending from saidreverse face of said lining carrier plate which are disposed at adistance from each other and which extend into at least twocorresponding apertures of said damping plate, at least one of saidapertures is oblong in shape and longitudinal extension of said oblongaperture extends in the direction of the connecting line between said atleast two apertures, said damping plate is attached to said liningcarrier plate by riveting of said at least two projections of saidlining carrier plate to said damping plate.
 9. A brake pad as claimed inclaim 8, wherein said at least two projections have substantiallycircular cross sections and are positioned in an external marginalranges of said reverse face of said lining carrier plate, and said atleast two projections being disposed substantially opposite each otherin the circumferential direction of said brake disc.
 10. A brake pad asclaimed in claim 9, wherein a third projection is positioned in a centerrange of said lining carrier plate and projects through a third apertureof said damping plate and by which a retaining spring of spring sheetsteel is riveted to said brake pad.
 11. A brake pad as claimed in claim10, wherein said third projection has a D-shaped cross section andprojects through a D-shaped aperture of said retaining spring.
 12. Abrake pad as claimed in claim 8, wherein said at least two projectionshave substantially circular cross sections and are positioned inexternal marginal ranges of said reverse face of said lining carrierplate, and said at least two projections being disposed opposite eachother in the radial direction of said brake disc on either side off thecenter of said brake pad.
 13. A brake pad as claimed in claim 8, whereinsaid at least two projections are molded outwardly from said liningcarrier plate.
 14. A brake pad for a disc brake, comprising:a liningcarrier plate, a damping plate, and damping plate attaching means, saidlining carrier plate having a front face for attaching to a brake liningand a reverse face, said damping plate attaching means connected betweensaid lining carrier plate and said damping plate for loosely couplingsaid damping plate to said reverse face of said lining carrier plate sothat relative movement is permitted during use between said liningcarrier plate and said damping plate.
 15. A brake pad as claimed inclaim 14, wherein said damping plate comprises a steel plate coated withrubber.
 16. A brake pad as claimed in claim 14, wherein said dampingplate attaching means includes at least two projections extending fromsaid reverse face of said lining carrier plates said projections havinga narrow portion and a widened portion; and at least two apertures madein said damping plate to respectively engage said projections.
 17. Abrake pad as claimed in claim 16, wherein said widened portion of saidprojections of said lining carrier plate is formed by wobble riveting.18. A brake pad as claimed in claim 14, wherein at least one of saidapertures is oblong in shape and longitudinally extends in the directionof the connecting line between said at least two apertures.
 19. A brakepad as claimed in claim 16, wherein said lining carrier plate isattached to said damping plate by way of riveting.
 20. A brake pad for adisc brake, comprising:a lining carrier plate, said lining carrier platehaving a front face and a reverse face, said reverse face including atleast two projections extending therefrom at a distance from each other,and said projections having a narrow portion and a widened portion; adamping plate, said damping plate having at least two apertures, saidapertures corresponding to said projections of said lining carrierplate, and said apertures having a diameter larger than diameter of saidnarrow portion of said projection of said lining carrier plate, and saiddiameter also being smaller than diameter of said widened portion ofsaid projection of said lining carrier plate thereby creating a spacefor movement between said damping plate and said lining carrier plate;whereby said widened portion of projections of said lining carrier plateextend beyond diameter of said apertures of said damping plate and presssaid damping plate against said lining carrier plate so that a slightlateral shift of said damping plate relative to said lining carrierplate in a direction parallel to the plane of said lining carrier plateis possible within the limits of the space for movement.
 21. A brake padas claimed in claim 20, wherein said damping plate comprises a steelplate coated with rubber.
 22. A brake pad as claimed in claim 20,wherein said widened portion of said projections of said lining carrierplate is formed by wobble riveting.
 23. A brake pad assembly for a discbrake, comprising:a lining carrier plate, a friction lining, and adamping plate, said lining carrier plate having first and second sidesand also having two spaced projections; said friction lining attached tosaid first side of said lining carrier plate for urging against a brakedisc; said damping plate including first and second openings adapted torespectively engage said first and second spaced projections forattaching said damping plate to said second side of said lining carrierplate; said two projections being positioned on said lining carrierplate in a location spaced from a region generally intended to transmitclamping forces to said brake disc; wherein, at least one of said firstand second openings is elongated relative to its respectively associatedprojection, wherein said elongation is generally in the direction of aconnecting line drawn between said two projections, whereby a pressureforce generated by attacking permits a slight parallel shift of thedamping plate in relation to the lining carrier plate.
 24. The brake padassembly of claim 23, wherein said two projections include asubstantially circular cross-section and are arranged in the externalmarginal ranges of the lining carrier plate in the circumferentialdirection of the brake disc opposite each other.
 25. The brake padassembly of claim 24, wherein the lining carrier plate includes a thirdprojection and wherein said assembly further includes a retainingspring, wherein said third projection is positioned in a central rangeof the lining carrier plate and projects through a third hole in thedamping plate, said third projection attaching said retaining spring tosaid assembly.
 26. The brake pad assembly of claim 25, wherein saidthird projection includes a generally D-shaped cross-section andprojects through a D-shaped opening in said retaining spring.
 27. Thebrake pad assembly of claim 23, wherein said two spaced projections havesubstantially circular cross-sectional areas and are arranged oppositeeach other on opposite sides of the brake pad in external marginalranges of the lining carrier plate along a radial direction of the brakedisc.
 28. The brake pad assembly of claim 23, wherein said two spacedprojections are shaped from the material comprising the lining carrierplate.
 29. The brake pad assembly of claim 23, wherein said dampingplate consists of a steel plate coated with rubber.